| Blesscafe&Deli Ltd | Hospitality | 2024 |
| Blessed (PVT) Ltd | Construction | 2019 |
| Blessed Hands Limited | Administrative & support | 2023 |
| Blessgold Healthcare Solutions Ltd | Other services | 2024 |
| Blessing Research Consultancy Ltd | Professional & scientific | 2021 |
| Bletchley Motor Company Limited | Professional & scientific | 1975 |
| Bletchley Motor Group Limited | Professional & scientific | 1982 |
| Bletchley Point Ltd | Information & communication | 2025 |
| Bletsoe Limited | Real estate | 1996 |
| BLG VAP Limited | Real estate | 2019 |
| Blind Box Empire Limited | Wholesale & retail | 2022 |
| Blind ING Property Ltd | Real estate | 2026 |
| Blinds 2 Go Limited | Wholesale & retail | 2000 |
| Blindside Trading Cards Ltd | Wholesale & retail | 2025 |
| Blinkbright Ltd | Professional & scientific | 2015 |
| Bliss & Blush Limited | Wholesale & retail | 2025 |
| Bliss Beauty Keyworth Ltd | Other services | 2025 |
| Bliss Entertainment Limited | Hospitality | 2017 |
| Bliss Property Solutions Ltd | Construction | 2019 |
| Blissett Projects Ltd | Construction | 2018 |
| Blissworld Global Ltd | Transport & logistics | 2025 |
| Blitz Competitions Limited | Arts & recreation | 2018 |
| Blitz Growth Partner & Consultancy Ltd | Professional & scientific | 2025 |
| Blitz Services Drains Limited | Construction | 2024 |
| Blkwte Clothing Limited | Wholesale & retail | 2025 |
| Blocbuster Ltd | Administrative & support | 2024 |
| Block a Beaufort Management Limited | Real estate | 1989 |
| Block B Beaufort Management Limited | Real estate | 1989 |
| Block C Beaufort Management Limited | Real estate | 1989 |
| Block Construction Limited | Construction | 2019 |
| Block E Beaufort Management Limited | Real estate | 1989 |
| Block Party Bakery Ltd | Hospitality | 2021 |
| Blockhaus Properties Ltd | Real estate | 2019 |
| Blonde Productions Limited | Information & communication | 2026 |
| Blood Brother Media Ltd | Professional & scientific | 2021 |
| Blood Money Media Limited | Administrative & support | 2006 |
| Bloodhound Tattoo Studio Ltd | Real estate | 2026 |
| Bloom by Katie B Ltd | Other services | 2025 |
| Bloom Promo Ltd | Manufacturing | 2017 |
| Bloom Social Care Limited | Professional & scientific | 2010 |
| Bloombar Trustees Limited | Financial services | 2024 |
| Bloomfields Welch Management Ltd | Arts & recreation | 2004 |
| Bloomiful Ltd | Wholesale & retail | 2021 |
| Bloomingpath Solutions Limited | Information & communication | 2026 |
| Bloomme Ltd | Wholesale & retail | 2025 |
| Bloommm Ltd | Professional & scientific | 2025 |
| Bloomora Network CIC | Health & social care | 2026 |
| Bloomsbury Court RTM Company Limited | Households | 2012 |
| Bloor Corporation Limited | Construction | 2024 |
| Blorenge Healthcare Services Limited | Health & social care | 2024 |
| Blossom & Wren Properties Limited | Real estate | 2025 |
| Blossom Tree Lettings Limited | Real estate | 2025 |
| Blossoming Limited | Professional & scientific | 2008 |
| Bloswood Interiors Limited | Construction | 1999 |
| Blot Consulting Ltd | Wholesale & retail | 2022 |
| Blousey Ltd | Wholesale & retail | 2022 |
| Blowfish Financial Services Limited | Financial services | 2005 |
| Bloxwich Radio Taxis Limited | Transport & logistics | 2018 |
| BLR Properties Nottingham Ltd | Real estate | 2023 |
| BLR9 Clothing Limited | Wholesale & retail | 2026 |
| Blrh Limited | Real estate | 2019 |
| BLU Banana Graphics Limited | Manufacturing | 2017 |
| BLU Barbering Limited | Other services | 2009 |
| BLU Bomma Ltd | Information & communication | 2024 |
| BLU Hair Limited | Other services | 2007 |
| BLU Point Logistics Limited | Transport & logistics | 2024 |
| Blucomms Ltd | Information & communication | 2010 |
| Blue 22 Solutions Limited | Information & communication | 2004 |
| Blue 365 Limited | Other services | 2023 |
| Blue Accounting UK Limited | Professional & scientific | 2008 |
| Blue ASA Services Ltd | Health & social care | 2022 |
| Blue B Consultancy Ltd | Professional & scientific | 2022 |
| Blue Badge Bunch CIC | Arts & recreation | 2024 |
| Blue Badge Designs Ltd | Manufacturing | 2004 |
| Blue Bagel Limited | Education | 2020 |
| Blue Bark (Leicester) Ltd | Manufacturing | 2023 |
| Blue Bell Hill Academy Trust | Education | 2013 |
| Blue Block Red Block Limited | Real estate | 2018 |
| Blue Brick Developments Ltd | Construction | 2017 |
| Blue Business Services Ltd | Professional & scientific | 2016 |
| Blue Cherry Management Ltd | Households | 2024 |
| Blue Circle Fish Bar Limited | Hospitality | 2006 |
| Blue Daisy Garden Design Ltd | Administrative & support | 2010 |
| Blue Daisy Gardening Limited | Administrative & support | 2015 |
| Blue Development Homes Limited | Construction | 2014 |
| Blue Dolphin Star Ltd | Wholesale & retail | 2025 |
| Blue Dove's Pets Ltd | Professional & scientific | 2023 |
| Blue Flag (Automotive) Limited | Administrative & support | 2024 |
| Blue Flame Plumbing and Heating Services Ltd | Construction | 2025 |
| Blue GAS and Plumbing Ltd | Construction | 2016 |
| Blue Heart Properties Limited | Real estate | 2023 |
| Blue Hedgehog Homes Ltd | Households | 2018 |
| Blue Horse Leisure Limited | Professional & scientific | 2004 |
| Blue House Publishing Ltd | Information & communication | 2021 |
| Blue Kangaroo Services Ltd | Professional & scientific | 2022 |
| Blue Lagoon Aquatics Limited | Administrative & support | 2002 |
| Blue Lets Limited | Real estate | 2018 |
| Blue Marlin Fish Restaurants (Nottm) Limited | Hospitality | 1967 |
| Blue Monkey Brewing Limited | Manufacturing | 2008 |
| Blue Monkey Estates Ltd | Administrative & support | 2009 |